Population ecology of polar bears at Svalbard, Norway

The population ecology of polar bears at Svalbard, Norway, was examined from 1988 to 2002 using live-captured animals. The mean age of both females and males increased over the study, litter production rate and natality declined and body length of adults decreased. Dynamics of body mass were suggestive of cyclical changes over time and variation in body mass of both adult females and adult males was related to the Arctic Oscillation index. Similarly, litter production rate and natality correlated with the Arctic Oscillation index. The changes in age-structure, reproductive rates and body length suggest that recovery from over-harvest continued for almost 30 years after harvest ended in 1973 and that density-dependent changes are perhaps being expressed in the population. However, the variation in reproduction and body mass in the population show a relationship between large-scale climatic variation and the upper trophic level in an Arctic marine ecosystem. Similar change in other polar bear populations has been attributed to climate change, and further research is needed to establish linkages between climate and the population ecology of polar bears.